In the U.S. Patent Application Ser. No. 43,361 filed May 29, 1979, a drawing appliance has been described that includes as a combination a fixed but replaceable stencil that is provided with a cutting of a certain shape intended to serve as a guide of the tracing part of stylus and with a support capable of receiving the tracings made by the tracing part, this support being rotatable so as to be able to be angularly displaced by successive steps.
In accordance with a particular form of the invention, the support intended to receive the tracings of the tracing part consists of a translucent screen that forms the upper part of a tight chamber containing a dust-like matter that is capable of adhering to the translucent screen, while the tracing part consists of a movable stylus located within the chamber and that is resiliently supported on the inner surface of the screen. The tracing stylus axially traverses the chamber bottom in a tight but articulate manner by control of the bottom end thereof which is connected by an appropriate system of rods to a control member of a "joy stick" type that is capable of being guided by the stencil. The tight chamber and the rod system are located on the same hollow housing in which light is emitted by the controlling part, and the housing also defines a repository for the replaceable stencil.
Such an appliance permits various kinds of more or less complicated geometrical forms as based on one or several stencils provided with cuttings of elementary shapes to be reproduced in a simple and ingenious manner. It is also possible to use the appliance for the direct production of drawings, without the use of intermediate stencils; however, in the latter case, the fact that the stylus tip is constantly supported by the inner surface of the screen constitutes a serious drawback because in such a case one cannot avoid the presence of the unsightly connecting lines between the different elements of the drawing.
The present invention is intended to cope with such a drawback, and to this effect, the invention is applied to a drawing appliance of the aforementioned type, characterized essentially by the circumstance that there is provided means for a temporary removal of the stylus point from the inner surface of the screen.
In a particular form of the invention a stylus rod system is supported by at least one movable bearing that is capable of being displaced under influence of a controlling lever, one end of which is accessible exteriorly of the device through an opening in the housing thereof.
It is understood that in this manner, by simply displacing a bearing of the rod system, the removal of the stylus from the screen can be accomplished without hindering the functioning of the rod system. It is therefore possible in this manner to place the stylus in any location with respect to the screen without creating tracings while moving the stylus, which further increases the application possibilities of the appliance, that is, permitting more complicated drawings of a better quality to be created.
Other objects, features and advantages of the invention shall become apparent as the description thereof proceeds when considered in connection with the accompanying illustrative drawings.